<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    var json = {
        "username": "zhangsan",
        "age": 23,
        "addr": ["北京", "上海", "西安"]
    };
    alert(json.username+json.age+json.addr);

</script>
</body>
</html>